I have never done relativity before, my uni professor isn't good enough and I can't understand a word he says, he's all over the place. Anyway I missed a week due to being sick, and I just can't catch up, I am struggling to find any textbooks that have similar notation or help me solve problems. They all assume I understand things like length contraction, time dilation, proper length, etc. This is an example of the simplest questions we have been asked: http://i.imgur.com/lHtbXPU.jpg What textbook, youtube video series, or whatever can I watch to catch up and learn about relativity? This is second year undergraduate physics.